1. Field of Invention
The present invention is related to a water-based ink for ink jetting comprising water, a water soluble organic solvent and a coloring agent as essential components. The present invention is also related to an ink jet recording method for recording by flying minute droplets of the ink.
2. Description of Related Art
In the ink jet recording method, ink droplets are formed by various ink jetting methods including the electrostatic suction method, a method of applying mechanical vibration or displacement using a piezoelectric element, or a method of generating bubbles by heating ink and utilizing pressure generated thereby, and recording is operated by adhering a part of or all of the formed droplets to a recording material such as paper. A lot of development of the water-based ink using water as a main solvent has been made for ink for the ink jet recording method.
The water-based ink for ink jetting needs to meet some conditions of no clogging at the head end portion of the recording apparatus or the ink passage, stable jetting, providing recording images of clear tone of color and sufficient high density and good water resistance and good friction resistance of the recorded matter.
Dye or pigment is generally used for a coloring agent of the water-based ink for ink jetting.
Pigment is better than dye in terms of water resistance; however, pigment is worse in terms of the liquid stability and the dispersion of the pigment becomes unstable by the long period preservation or the water evaporation because pigment is not dissolved but is dispersed in the ink medium. Therefore, compared to the dye ink, the pigment ink is easy to cause clogging at the end portion of the head of the ink jet printer or in the ink passage. Because the pigment exists as a particle on the recorded matter, it has a problem in terms of the friction resistance. Therefore, it is a rare case that the pigment ink for the ink jet printer has become a commercial product, and most of the pigment ink is in the development stage.
Although the water soluble dye is worse in terms of the water resistance compared to the pigment, the dye ink is hardly clogged at the end portion of the head of the ink jet printer or the ink passage and it is possible to acquire relatively easily a recorded matter of clear color tone and high density because the water soluble dye is completely dissolved in the ink medium. Therefore, there are many cases that the water-based ink for ink jet printer using water soluble dye as a coloring agent has become a commercial product.
However, there has been no example of water-based ink for ink jetting that meets all conditions of sufficient jetting stability of ink jet recording, and clearness, high density recording, water resistance and friction resistance of the recorded matter.